Horton

Re: hung backends stuck in spinlock heavy endless loop

Peter Geoghegan <pg@heroku.com>

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From: Peter Geoghegan <pg@heroku.com>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>, Andres Freund <andres@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-01-15T18:47:05Z
Lists: pgsql-hackers 
On Thu, Jan 15, 2015 at 6:02 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
> Question: Coming in this morning I did an immediate restart and logged
> into the database and queried pg_class via index.   Everything was
> fine, and the leftright verify returns nothing.  How did it repair
> itself without a reindex?

Maybe the relevant WAL records are more or less correct, and recovery
restores the database to its correct state, as opposed to the state it
was actually in at the time of the crash due to a race condition or
whatever. Could you possibly send bt_page_items() against block 9 of
the index after recovery? It probably looks totally sane, but it would
be nice to be sure, if you happen to still have the data.

-- 
Peter Geoghegan

Commits

  1. Improve hash_create's API for selecting simple-binary-key hash functions.

  2. Fix WAL-logging of B-tree "unlink halfdead page" operation.

  3. Fix backup-block numbering in redo of b-tree split.

  4. Cleanup of new b-tree page deletion code.

  5. Fix bug in the new B-tree incomplete-split code.

  6. Fix bug in new B-tree page deletion code.

  7. Fix rm_desc routine of b-tree page delete records.

  8. Make the handling of interrupted B-tree page splits more robust.

  9. Fix race condition in B-tree page deletion.